a/c problem

[bump530]

i doubt this is the correct section but i didnt see one that it would fit in. but anyways, heres my problem:

the a/c works great for a while, then all the sudden hardly any air comes out the vents. you can still hear the fan motor blowing and it even adjust from low-high, but the air flow is about the same. if i turn the a/c off for a little while, and then turn it back on, it works fine for a few minutes or so. ive read that a vacuum line may be causing this but i have no clue as to wear to start looking. anybody know whats going on here?

 

[Aloicious]

is the air getting really cold? if so, its possible the temps at the evaporator are reaching water freezing point, and the humidity is frosting up the evaporator restricting the airflow. if you have an A/C gauge you can check the low pressure side of the A/C and see what it is. R134a is colder at lower temperatures, so if you're a little low, that could be causing it. here's a temperature chart for R134a based off pressure:
http://www.csgnetwork.com/r134apresstempconv.html

its a thought. probably other things could be causing it as well.

 

[Mike]

It sounds like if the above isn't it that a vacuum line that operates the air valves is leaking or broken. I've never had to go through mine so I'm not sure where they are on the trucks but on the older cars its pretty easy to follow the lines that control the vents. Worst comes to worst you could find the offending vent and jam it open forever and that will be that.

 

[frito-bandito]

Feel your accumalator and see if it has ice on it when it stops blowing.

 

[bump530]

aight ill look into all them and let yall know what i find. thanks

 

[frito-bandito]

I just read your signature, you have a lot of mods that id like to do to my 98 2wd, post some pics of your truck!!

 

[LPG PWRD]

hows your fan/fans? do you have efans? or is your clutch fan not as loud as it used to be?
9 times out of 10 with this condition of blowing cold, then after while warm, turn off for a bit then turn back on and majic cold air comes back out is high side pressure is getting too high.

good pressures:
low side 35-40 psi
high side 225-260 psi

with out the fan moving the correct amount of airflow over the condensor it will climb up to 400-450psi

try sticking a fan in front of the grill and see if it works longer.

or just start the truck cold and rev it up a little, the clutch fans on these trucks are loud as hell, if its not loud and you dont feel a **** ton of air movement, get a new fan clutch.

 

[Aloicious]

I believe he's referring to the actual volume of air coming out of the vents which is changing durring a drive, not the temperature.

 

[bump530]

hows your fan/fans? do you have efans? or is your clutch fan not as loud as it used to be?
9 times out of 10 with this condition of blowing cold, then after while warm, turn off for a bit then turn back on and majic cold air comes back out is high side pressure is getting too high.

good pressures:
low side 35-40 psi
high side 225-260 psi

with out the fan moving the correct amount of airflow over the condensor it will climb up to 400-450psi

try sticking a fan in front of the grill and see if it works longer.

or just start the truck cold and rev it up a little, the clutch fans on these trucks are loud as hell, if its not loud and you dont feel a **** ton of air movement, get a new fan clutch.

its not that it blows hot air, its that it doesnt move much air, like its blocked off somehow, but u can hear the blower working.

i have a slight freon leak and it seems that i finally lost enuf (after about ayear) for it to stop blowin cold. gonna fix that this weekend and see if that dont help things out.

 

[bump530]

I just read your signature, you have a lot of mods that id like to do to my 98 2wd, post some pics of your truck!!

aight. i got to take some of it with the tires. for years i had just 2" drop shackles in the back with 275/60s on it (which if the first pic). the second pic is with the 2" springs on front and stock shackles on the back.